docs: async def write_and_drain(self, data: bytes, timeout: NumType = None) -> None:
          """
          Format a command and send it to the server.
          """
          if self._stream_writer is None:
              raise SMTPServerDisconnected("Client not connected")
  
          self._stream_writer.write(data)
  
          async with self._io_lock:
              await self._drain_writer(timeout)